Because landlords are in the catbird seat with this kind of demand, effective rent -- the rental rate averaged out over the term of the lease and giving consideration for rent-free periods or up-front incentives -- rose 3.7 percent during the 12 months ending in May, Axiometrics reported.

"The year-to-date effective rent growth numbers portray an apartment market that may be having its strongest year since the Great Recession ended," said Jay Denton, Axiometrics vice president of research.

The increases were felt even more strongly by renters in Southwest Florida, where effective rent rose 7.51 percent.

That was the 10th-highest increase nationwide, according to Axiometrics. In Florida, only Naples-Marco Island saw a bigger increase, at nearly 8.5 percent.

Occupancy was at 94.8 percent in April 2014, also the previous monthly high. Occupancy was previously at that level in August and September.

"The national occupancy rate has increased steadily each of the past four months," said Stephanie McCleskey, Axiometrics' director of research.

About 180,000 new units have been built in the United States during the past 12 months, but with high absorption, rent has continued to rise.

"One reason occupancy is rising is that not only are people moving into these new units, but they're also moving into Class B units at a lower price point," McCleskey said.

"Most of the new units are priced competitively with Class A product, so about 80 percent of existing stock has lower rents than the newcomers, making them attractive to those who can't afford the highest rents."

Landlords are getting a higher percentage of so-called "asking rent."

Concession values -- breaks on rent -- were at a post-recession low for the second straight month, decreasing slightly to 0.8 percent in May 2014 from 1 percent in April.

Despite the drop, concessions are still equivalent to four days' free rent on a 12-month lease.

<p>National apartment occupancy hit 95 percent during May -- a level not seen since at least 2006, when the real estate market was still booming, according to an apartment data and research company.</p><p>Because landlords are in the catbird seat with this kind of demand, effective rent -- the rental rate averaged out over the term of the lease and giving consideration for rent-free periods or up-front incentives -- rose 3.7 percent during the 12 months ending in May, Axiometrics reported.</p><p>"The year-to-date effective rent growth numbers portray an apartment market that may be having its strongest year since the Great Recession ended," said Jay Denton, Axiometrics vice president of research.</p><p>The increases were felt even more strongly by renters in Southwest Florida, where effective rent rose 7.51 percent.</p><p>That was the 10th-highest increase nationwide, according to Axiometrics. In Florida, only Naples-Marco Island saw a bigger increase, at nearly 8.5 percent.</p><p>Other Florida markets on Axiometrics list of the 25 highest effective rate increases were: Cape Coral-Fort Myers (15th, with a 6.3 percent increase), Miami (16th, 6.29 percent), West Palm Beach (19th, 6.03 percent), Palm Bay-Melbourne (24th, 5.55 percent) and Fort Lauderdale (25th, 5.51 percent).</p><p>Occupancy was at 94.8 percent in April 2014, also the previous monthly high. Occupancy was previously at that level in August and September.</p><p>"The national occupancy rate has increased steadily each of the past four months," said Stephanie McCleskey, Axiometrics' director of research.</p><p>About 180,000 new units have been built in the United States during the past 12 months, but with high absorption, rent has continued to rise.</p><p>"One reason occupancy is rising is that not only are people moving into these new units, but they're also moving into Class B units at a lower price point," McCleskey said.</p><p>"Most of the new units are priced competitively with Class A product, so about 80 percent of existing stock has lower rents than the newcomers, making them attractive to those who can't afford the highest rents."</p><p>Landlords are getting a higher percentage of so-called "asking rent."</p><p>Concession values -- breaks on rent -- were at a post-recession low for the second straight month, decreasing slightly to 0.8 percent in May 2014 from 1 percent in April.</p><p>Despite the drop, concessions are still equivalent to four days' free rent on a 12-month lease.</p>